But Sirius
by Loki Mischeif-Maker
Summary: Sirius and Remus are in the library, and Sirius happens to notice that Regulus is sitting next to a girl. A little too close to a girl for big brother's comfort. So big brother proceeds to make a fool of himself.


**Disclaimer:** I do not own Remus, the Blacks, Hogwarts, or anything else you recognize— and I promise not to hurt them, either.

"Sirius. . . ?" Remus asked, leaning over to shake his friend on the arm. "What's up?"

"Nothing!" Sirius snapped back, just a little too defensively.

Remus sighed and set the book he was reading down. "First of all, don't snap at me in the library unless you want Pince to kick you out," he said softy. "Second of all, you're not concentrating, but you're letting me concentrate. That never happens. Something's wrong."

"I don't see how it concerns you, Remus," the other fourteen-year-old hissed. "Since I'm not, after all, bothering you in the least."

"No, but you're worrying me," Remus answered tiredly. "Now what is going on?"

"For the last time, _nothing_! Well, it had better be nothing," Sirius amended. For the entire conversation thus far, his gaze had not moved from a table halfway across the library. "It's Reggie."

Remus followed his gaze to see Regulus Black and a girl wearing a scarf in Slytherin colors leaning over the same book. Regulus was rather closer to her than he probably absolutely had to be, and as Remus watched he said something to her and she laughed. Sirius's scowl, on the other hand, only deepened.

"You're a filthy hypocrite, you know that?" Remus asked absently. "_You_ started dating last year, why can't he date in third year, too?"

Sirius shook his head. "It's not that he's dating—"

"You're lying through your teeth, Sirius, I can tell," Remus interrupted. "For one thing, if you weren't you'd have yelled at me for calling you a hypocrite, and that would require taking your gaze off the two of them. But you won't, because you're afraid you might miss them doing something that you don't entirely approve of when someone does it to _him_. You don't, on the other hand, seem to mind when a girl does it to _you._"

Sirius shook his head again. "All right, I'm a hypocrite. But it's still not so much that he's dating as _who_ he's dating. That's Marcia Flint."

"I really hadn't noticed," Remus told him dryly, flipping a page in his book.

"Marcia Flint," Sirius repeated, as if he couldn't quite believe it. "She's . . . she's an idiot. She can't even cast the Leg-Locker Curse right. She tried to do it to Peter the other day—"

"If you had been there for the entire scene, Sirius, you would have heard what Peter had compared her brother to, and then maybe you wouldn't blame her for trying quite so much. And it's harder to make any spell work when you're boiling mad. _You_ of all people should know that."

"And she's not even that attractive," Sirius added, clearly ignoring Remus, which was irritating but hardly unusual.

"Well . . . she is someone your mother would approve of, isn't she?" Remus asked, trying to get through to him. "And doesn't Regulus care about who Mrs. Black would approve of?"

"Damn whoever my mother would approve of," Sirius answered irritably. "I'm sure there's someone on that list who's reasonably attractive or at least intelligent."

"Honestly, Sirius, your criteria for choosing girls is awful."

"Frankly, Remus, I'd rather have both, but I'll settle for pretty if my hormones get the better of me." He shook his head. "I can't believe he's dating. Only last year he was still crawling into my bed if there was a big enough thunderstorm."

"I'm fairly sure you're exaggerating."

"Only a little," Sirius admitted.

Remus sighed, mentally calling Sirius several kinds of idiot for acting like this. "Sirius, there's something I ought to tell you before this conversation gets out of ha—"

"She's getting up. I'm going to talk to him."

"Merlin, no," Remus muttered, shutting the book and standing up to go after his friend before he made a fool of himself.

☐☐☐

"This time next week?" Regulus asked.

Marcia nodded. "Thanks," she told him, picking up her Transfiguration book, shoving it into her bag, and making her way out of the library.

Regulus turned around to go back to his own homework, but Sirius had been standing almost directly behind him and scowling. "Yes, Sirius?" he asked, trying to keep his voice as even as possible and wondering why his brother was about to yell at him.

"Wasn't that Marcia Flint that just walked out of here?" Sirius asked in a voice of forced calm.

"Unless someone's been taking Polyjuice Potion around here, yes it was," Regulus answered, shrugging. "Why do you ask?"

"I can't believe you," Sirius declared, loudly enough that several people nearby turned around to stare. "She's an idiot and she's not even pretty. I frankly don't _care_ what Mum says about your girlfriend, you can do better than _Marcia Flint_. I mean, I'm sure there are plenty of girls in Ravenclaw that you could get away with dating, and they're more your type anyway."

"How do you know what's my type?" Regulus muttered.

"I'm your brother! I've only lived with you for the past thirteen years!" Sirius exclaimed. "I mean, and that's only if you absolutely must to date someone. After all, you are a bit young—"

"You were dating this time last year," Regulus pointed out, now slightly irritated. "And besides—"

"That is completely beyond the _point_, Reg, and still, _Marcia Flint_?"

"_Sirius—_"

"The girl who can't even cast the Leg-Locker Curse properly when she's thirteen? Who—"

Regulus had no doubt Sirius could keep going for an hour about Marcia's stupidity, or her rather plain looks, or how she was apparently not Regulus's type, despite the fact the Regulus was still trying to decide what kind of girls _were_ his type in the first place. From there he would undoubtably move on to why Regulus shouldn't be dating at all yet. He just didn't want to hear it, so instead he reached for the heavy-looking book Remus Lupin, who had come up with Sirius and was looking rather embarrassed, was holding. "I'm going to borrow this for a minute, Lupin," he whispered.

Lupin let go of it willingly. "If you get his brains on it, you're buying me a new one."

Regulus grinned absently and nodded. "Fair enough." Then he hit his brother over the head with it. It made a satisfying crack as he did so.

Sirius was not brained, but the effect was still immediate. "Ow!" he cried, reaching up to rub his crown. "What was that for?"

"First of all, it was the only way to get your attention, and you're going to get all three of us thrown out of the library if you keep that up," Regulus answered. "What was it really for? For being an idiot."

"And how was I being an idiot?" Sirius demanded. "I think I'm going to get a lump where you hit me," he added in what was nearly a moan.

"He's not dating her," Lupin supplied.

"_What_?"

"I am not dating Marcia Flint," Regulus repeated, handing Lupin back his Runes book and marveling at the thickness of his big brother's skull. "And I'm aware she's not the brightest person in the world. It's why I'm tutoring her in Transfiguration."

"Are you?" Sirius asked, utterly bewildered.

Regulus and Lupin both nodded.

"Well, I feel stupid now," Sirius admitted, rubbing his head. "Remus, you could have told me."

"I tried. You wouldn't listen," Lupin answered.

Sirius dismissed this and turned back to his little brother. "Well, I'm glad to hear you're not dating yet. But that really did _hurt_."

"Go see Madame Pomfrey," Lupin suggested, shoving him in the direction of the door. "And if she asks, not that she would with you anymore, you can just tell her you were being stupid again, so your brother tried to knock some sense into you."

Sirius listened to him for once and left, muttering.

"Hypocrite," Regulus said absently, watching him leave.

"Well, you _can_ do better than Marcia Flint. And he's just trying to look out for you," Remus answered with a shrug.

"Yeah, I s'pose," Regulus admitted. "But Lupin?"

"Yes?"

"If he has enough sense to ask how you knew I wasn't dating Marcia and you tell him that you caught me snogging Liza Nott the other day, I am going to experiment with all those inventive little ways Muggles had of killing wizards back in the sixteenth century."

Lupin laughed and ruffled his hair, rather like Sirius might have. "Fair enough, Black," he answered cheerfully. "Sirius would probably have another near heart attack, anyway."

* * *

**Author's Note:** This is all snape'smistress-in-law's fault. I mean it. In chapter six of The Worst Mistake (which you should check out) I started wondering how Sirius and_my_ characterization of Reggie might react to Regulus's first girlfriend. How it got twisted into this is something I haven't quite figured out,and I still might do a longer, slightly more serious fic on the subject. Until then (and if),Cheers! --- Loki 


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